Transfer printing process for leather



Feb. 2, 932 A, SCHUBERT 1,843,741

TRANSFE PRINTING PROCESS FOR LEATHER Filed May 9, 1930 'I M.. "u .,Ih A|||||||IIIII IN VEN TOR.

B MW# A TToRNEYs.

Patented Feb, 2, i932 narran sra/tres tatami ADOLF SCHUBERT, 0E MEILLEURE', NEW FERSEY, ASSEGNOR TO BARRETT & COMPANY, Ol NEWARK, NEW JERSEY, A CORPORATN 01E' NEW JERSEY TRANSFER 'BMNTENG PROCESS FOR LEATHER Application :filed May 9,

'l`his invention relates to the application to the marking lof leather, of a transfer-printing process that l have developed for making permanent markings on fibrous articles and which is peculiarly suited for ornamentation Work. yllhe present invention concerns protecting the leathers against a deleterious action Which the chosen dye solvent may have.

Hereinafter, for simplicity of expression, l shall frequently refer to ink as incorporating a single dye (singular number) it will be understood however, that any given ink may contain two or more dyes.

ln this process, the subject matter (letters, numerals, lines, masses of colors, pictures, etc., etc.) is laid down in an ink containing an undissolved dyestu or dyestuffs, and then the dyestu is transferred to the article or material ultimately intended to receive the marking by contact in the presence of a transfer agent, so-called, which is or includes a solvent for the dyestuff or dyest'uffs, and which solvent is capable, or is made capable, of permeating the vehicle portion of the ink. Sheets of paper, cloth, or the like, on which the subject matter may be printed and from which the transfer is thus made, are called transfer sheets.

ln applying my process thus briefly outlined to the ornamenting of leather, l use as the dyestud in the ink a dye capable of dyeing leathers or skins, rather than, forexample, a discharge, mordant or resist, and it frequently happens that a desired solvent Afor the dye, used in transferring the dye to the leather, is a substance that has a deleterious action on the leather. For example, the alcohols, and particularly ethyl alcohol, are desirable substances for use as the dye solvent in-making the transfer to leathers; ethyl alcohol however has a deleterious action on the vegetable tanned leathers and some of the chrome tanned leathers; it tends to extract the tannin.

The object of the present invention is to avoid this deleterious action, and this l now propose to do by so treating the leather that a compound, substantially insoluble in the transfer agent, is formed With the tannic acid on or in the fibres of the leather. Preferably 1930. Serial No. 451l96.

the compound formed is one which is transparent or colorless; that is to say, the cornpounds should be transparent or colorless except Where opacity or color may not be objectionable, To form such an insoluble compound with the tannic acid, ethyl alcohol being used as the dye solvent, calcium and barium salts are preferred; particularly cal cium bromide and barium bromide; and most preferably calcium bromide.

ln applying my present invention therefore: ll use as the ink, one incorporating a dye capable of directly dyeing the leather to be Worked on (using the term dye with the meaning hereinafter given to it), and usually an alcohol-soluble dye. With the chosen dye, there is mixed a vehicle to suit the particular conditions under Which the subject matter is laid down for transfer of the dye to the leather, as suiting the particular printing process selected for printing on paper sheets; thus for printing on sheets of paper, cloth or other similarly light thin flexible materials, the vehicle material is so Chosen that the ink resulting from the mixture has that viscosity, tacky or greasy nature, or Whatever other characteristics may be required of the ink used in the particular printing process employed for laying down the ink on the sheet. Furthermore, lf choose for the vehicle a substance or substances that Will remain on such transfer sheets until the transfers are made to the leather; ll believe that the presence of the vehicle at the time the transfer is made helps to confine the dye to its intended boundaries. rlhe dye is not to be held in the4 vehicle in solution however, but in a solid state; in suspension as it were. lf the dyestuff is soluble in the vehicle, bleeding may take place in the transfer sheet and this result in blurred outlines and poor color gradations in the reproduction on the leather. Furthermore, for certain colors, l have seemed to find it impossible to get suflicient dye into the vehicle in dissolved form to give the desired colored intensity in the reproduction. Hence l use as the vehicle portion of the ink (including in that term everything in the ink excepting the dye), a material or materials in Which the dye is substantially insoluble. Conceivably the dye may be intro duced into the vehicle initially in the form of a solution, if desired, provided the solvent is evaporated `later for example, or if the dye is precipitated or is otherwise restored to or produced in a solid state prior to printing on the transfer sheet base; at the time of the printing of the transfer sheet however, substantially all the dye should be in an undissolved state, but it should remain in this solid state until the time for making the transfer to the leather. Preferably therefore, l take the dye in powdered form and grind it into the chosen vehicle. Afterwards this mixture can be thickened if too thin, or thinned if too thick, by the addition of suitable inert substances as Will be understood; also drying retardants and/or other useful substances can be incorporated in and made a part of the ink as desired, and as will be understood.,

lilith such an ink ll usually print up a stock of transfer sheets at one time; that is to say, l print the subject matter on such a quantity 1 of sheets of paper, cloth or other relatively light thin flexible material as may correspond to the number of skins or pieces of leather to be marked, or as may be needed for some time to come. Preferably l use a fibrous material for these transfer sheet bases, because of the permeability of the fibrous materials. Newsprint paper is suit.- able and usually gives better results than a heavily sized paper. rlhe stock of transfer sheets can be used as needed so long as the subject matter remains clear and the vehicle remains on the transfer sheets and remains permeable to the dye solvent employed at the time of the transfer, or remains in a condition where it can be made permeable to the dye solvent.

To make a transfer or print on a leather the ink is brought into contact with the leather, as by pressing one of the transfer sheets smoothly to the leather, inked face to the leather, in the presence of a solvent or solvents of the dye. Preferably the solvent or solvents for the dye are chosen from those substances that have a high degree of capillarity with respect to the leather to be marked, and the particular kind of leather to be marked; that is to say, preferably the dye solvent or solvents is or are a substance or substances which penetrates and diffuses rapidly through the particular leather to be marked, as explained in a co-pcnding application for patent. Serial No. 448,434, filed April Q9, 1930. ln addition, the solvent or solvents for the dye must enter readily into the vehicle part of the ink. and be capable of carrying dye, or the needed dyeing principle from well within the vehicle into dyeing relation with the fibres of the leather. ln order that the dye solvent may enter the vehicle, the materials composing the vehicle and the' dye tatami solvent (or one of the latter) may be so chosen with respect to each other that the dye solvent has this characteristic of and by itself; for example, the dye solvent may be a solvent for the ink vehicle also. ln the alternative, an additional substance may be employed to give the dye solvent access into the vehicle; the latter is the subject of a co-pending application of mine, Serial No. 448,435, filed April 29, 1980; the additional substance, say a solvent for the vehicle, can be applied separately to the ink, or as a mixture with the dye solvent or solvents. Where the dye appears in the ink as a compound needing to be broken up, or Which can be broken up, before its action on the fibres is accomplished, (for example where the dye is in the form of a lake), the dye solvent can be selected for its ability to break up the compound, as Well as dissolve the dye; or in the alternative, an additional substance may be used, say along with the dye solvent, to break up the compound; the dye solvent need not then be a solvent for the dye compound found in the ink; it only need be a solvent for the dye proper, or the essential principle needed for dyeing the leather. Usually l apply the dye solvent to the leather, either by spraying or dipping immediately before the transfer, and apply the transfer sheet direct to the wetted leather. lWhen two or more solvents are used, and also when an additional substance is to be used at the time of making the transfer, such for example as a. substance to give the dye solvent or solvents access into a vehicle into which it or they are otherwise substantially impermeable, ll usually mix the whole and apply the mixture in the same way. Usually, too, l press the transfer sheet to the leather with considerable pressure, as in a-press, in order to evenly and uniformly contact the transfer sheet with the leather, the latter ordinarily varying considerably in thickness throughout its extent: ll have used up to 300 lbs. per square inch. This is not to be understood to indicate. however, that such high pressures as this are always necessary. Heat may be used simultaneously, as by passing steam through pipes provided in the plates of the press; heat is not altogether an essential however. The transfer of dye to the leather takes place rather quickly, at least under high pressure, a transfer of an adequate quantity of dye being produced in from a fraction of a minute to two minutes. The length of time the transfer sheet is left in contact with the leather does not seem to be critical however: for example, without heat lt have left a transfer sheet in contact with a leather. under pressure. for as much as five minutes without producing noticeable bleeding or blurring. lWhen the transfer has been accomplished, the transfer sheet is peeled off the leather of course. Preferably, lt employ dye solvents that are also volatile, so that they are readily llO Leraar/ii.

removed or escape naturally from the leather by evaporation after having performed their functions. For general use on leather l prefer the alcohol-soluble dyes, and as the dye solvent employed in making the transfer, l prefer-ethyl alcohol, denatured or not.

Where the chosen dye solvent or dye solvents have a deleterious a'ect on the leather chosen to be marked, by convertingV or otherwise extracting a substance therefrom, as ethyl alcohol tends to aect the tannin in vegetable tanned leathers and some chrome tanned leathers, l propose (according to the present invention) to avoid this deleterious action by applying to the leather, as mentioned before` a substance which forms a compound with the substance attacked by the dve solvent. which compound is insoluble in the d ve solvent or solvents, and, preferably, which is transparent or colorless. T he time and manner of the application of this substance to the leather is not material, generally speaking'.

Solids can be applied in the form of solutions. The protective substance or substances may be applied separate and apart from the transfer agent. or separate and apart from some of the substances used at the time of transfer when a multiple substance is employed in effecting; the transfer: for example, the protective substance or substances may be applied to the leather before the dve solvent is applied to the leather, when the dve solvent is applied to the leather itself rather than to a transfer sheet. Preferably, however'` the protective substance or substances is or are mixed with the dye solvent, for example, dissolved in the dye solvent, and the two applied as a unit. l

It will now be apparent th at Various kinds of dyes can be used in the ink. and the exact nature of the dye employed is not materia to my invention, excepting only that it be a dye capable of dyeing the leather. as the term dyeing is .used in. the dyeingart, and not a. mere. fixing' of pigment to the leather by the vehicle of the ink after the manner of printing. The dye may be a substance capable as a whole of dyeing the leather, or it may be a compound. such vas a lake, from which the dyeing principle is to be extracted; the'matter of lakes hasbeen mentioned above. For developed colors, or other dves acting in analogous ways. all of the constituents mav be incorporated in the ink when the conditions are suitable, or only a part of the constituents may appear in the ink and when necessary the remainder applied directly to the leather either before or after the transferringr operation. ln general, the various forms which the dye mav assume will be understood by those skilled in the art, who will understand also the various manners in which the leather may be treated, either before or after the transferring is done, o r both l' vehicle of the ink 7lhe ratio of the dye to the vehicle is found by trial, that ratio being used which gives the desired color strength or tinctorial value of the leather. With the ink thus formed, the design or ornamental matter is printed on sheets of such paper as is used for news print, using blocks or rolls etched or enff rraved, or otherwise marked in accordance with the desired design, as the printing' process may demand. Usually print up a stock of these transfer sheets at once, since this ink will remain permeable to the dye solvent hereafter specified for quite awhile. For the transfer agent, I employ a saturated solution of ethyl alcohol. denatured or not, and calcium bromide, when transferringf to a leather containinfr tannin subject to attack by the alcohol. When it comes time to make a transfer to, say, a vegetable tanned leather, the leather is sprayed with or dipped into the saturated solution of ethyl alcohol and calcium bromide. and immediately thereafterone of the transfer sheets is laid on the leather, inked `face to the leather, and the two pressed momentarily in a press to evenly and uniformly contact the transfer sheet with the leather; a rather soft pad may be imposed between the transfer sheet and the adjacent plate of the press to aid this action. The rosin oil being soluble in the ethylalcohol, the ethvlalcohol penetrates well into the ink immediately upon this contact, dissolves more or less of the dye, and carries the same into the midst of the fibres of the leather to which it thereupon` becomesyaffixed; that is to say. dyes the leather. Furthermore, on

the application of the alcohol-calcium-bromide solution to the leather, the calcium bro- -mide, entering the leather alone with the alcohol, forms with the tannic acid of the leather a compound which is insoluble in the. alcohol, so that the leather is protected against the deleterious action ofthe latter. After pressing the transfer sheet to the leather for a moment, the two are taken from the press and the transfer sheet is peeled off.

lt will be understood from the foreifroing that my invention is not limited to the details of the foregoing description, except as appears hereafter in the claims. Furthermore. it will be understood that when l use the word compound in describingthe `action between tannin andthe protective substance or substances, lf am using this Word compound in a rather broad sense, for example as includin g lakes, rather than in the narrow sense with which this word compound is sometimes used in chemistry in describing chemical reactions.

l claim:

l. In the method of making markings on leather, which consists in producing the subject matter in an ink incorporating a dye capable of dyeing the leather and vehicle material suiting the particular process by which the ink is laid down, and in which vehicle the dye is substantially insoluble, and pressing the subject matter, formed by such ink, to the leather in the presence of a solvent for the dye capable of carrying dye from the ink into the midst of the fibres of the leather, the improvement, Where a substance used at the time of making the transfer to the leather has a deleterious affect on the leather, which consists in applying to the leather a material capable of forming with the part of the leather attacked by such substance, a compound on which said substance used at the time of transfer has substantially no a'ect.

2. in the method of making markings on leather, Which consists in printing the subject matter on transfer sheet bases With an ink incorporating an alcohol-soluble dye for the leather and a vehicle material suiting the ink to the particular printing process by which the printing onto the transfer sheet bases is done, 'and in which vehicle the dye is substantially insoluble, and pressing, While the ink vehicle is still present on the transfer sheet, a transfer sheet to the leather in the presence of alcohol, the improvement, Where the alcohol tends to affect tannin in the leather, which consists in subjecting the leather to a substance forming a compound with the tannin which is insoluble in the alcohol.

ln the method of making markings on leather' which consists in printing the subject matter on transfer sheet bases with an ink incorporating an alcohol-soluble dye for the leather and vehicle material suiting the ink to the particular printing process by which the printing onto the transfer sheet bases is done and in Which vehicle substantially all the dye exists in an undissolved state, and pressing, While the ink vehicle is still present on the transfer sheet, a transfer sheet to the leather in the presence of alcohol, the improvement, Where the alcohol4 wearer leather which consists in printing the subject matter on transfer sheet bases with an ink incorporating an alcohol-soluble dye for the leather and Vehicle material suiting the ink to the particular printing process by which the printing onto the transfer sheet bases is done and in Which vehicle substantially all the dye exists in an undissolved state, and pressing, While the ink vehicle is still present on the transfer sheet, a transfer sheet to the leather in the presence of alcohol, the improvement, Where the alcohol tends to have a deleterious affect on the leather, which consists in applying to the leather, at least as early as the time When the alcohol is applied to the leather, a substance forming with the tannin of the leather a compound which is unaffected by the alcohol.

The method of making markings on leather which is deleteriously affected by alcohol, which consists in printing the subject matter on transfer sheet bases with an ink incorporating an alcohol-soluble dye for the leather and vehicle material suiting the ink to the particular printing process by which the printing onto the transfer sheet bases is done, and 1n which vehicle substantially all the dye exists in an undissolved state, applying as a unit to the ink on one of said transfer sheets, While the ink vehicle is still present thereon, a solvent for the dye capable of carrying dye from the ink vehicle into dyeing relation to the fibres of the leather and a substance forming with the tannic acid of the leather a compound Which is un` affected by the alcohol, and then pressing the transfer sheet to the leather.

6. The method of making markings on leather which is deleteriously afeeted by alcohol attacking tannin therein, which consists in printing the subject matter on transfer sheet bases with an ink incorporating an alcohol-soluble dye for the leather and vehicle material suiting the ink to the particular printing process by which the printing onto the transfer sheet bases is done and in which vehicle material substantially all the dye exists in an undissolved state, applying as a unit to the leather alcohol and a substance capable of forming with the tannin of the leather a compound which is substantially unaffected by the alcohol, and pressing,kwhile the ink-vehicle is still present on the transfer sheet and the leather is still Wet with said alcohol, a transfer sheet to a Wet surface of the leather.

7. T he method of making markings on leather Which is deleteriously affected by alcohol acting on tannin therein, Which consists in printing the subject matter on transfer sheet bases with an ink incorporating an alcohol-soluble dye for the leather and vehicle material suiting the ink to the particular printing` process by Which the printing onto the transfer sheet bases is done and in which substantially all the dye n in an unissolve state, applying alcohol and calcium bromide, and pressing, while the ink-vehicle is'still present on the transfer 52 sheet, the transfer sheet to the leather in tlfe presence of the alcohol.

8. rlFhe method of making cohol acting on tannin therein, which consists, in printing the subject matteron transter sheet bases with an ink incorporating an alcohol-soluble dye for the leather and vehicle material suiting the yink to the particular printing process by which the printing onto the transfer sheet bases is done, and in which substantially all the olye exists in an undissolved state, applying' ethyl alcohol and calcium bromide, and pressing, While the ink-Vehicle is still present on the transfer sheet, the transfer sheet to the leather in the presence of the alcohol.

ln testimony whereof, li have signed this4 specification.

wenn seirnnnar.,

wearer markin on y Y l leather which is (leleteriously affected si :Ll- 

